Martensitic transformation of a CuZnAl-shape memory alloy strengthened by hot-rolling

Lattice defects were introduced into stable austenite (β) of a CuZn27Al 4 alloy by a hot-rolling and quenching process (ausforming, AF). The amount of deformation was varied between zero and 1.54, the AF temperatures T(AF) between 800 and 650°C. At T(AF)<700°C the alloy forms a mixture of (α+β) phase and is rendered untransformable, while the other ausforming treatments do not reduce transformability. They lower the temperature range of martensitic transformation cycles and improve considerably the conventional strength properties. The interpretation of these results is based on the microstructure, especially the defect structure in austenite.